Hydrogen-induced atomic deformation in SrBi2Nb2O9 perovskite structure

Abstract

The origin of hydrogen-induced structural deformation of ferroelectric SrBi2Nb2O9 (SBN) thin films is investigated by annealing in forming gas (3% H-2-97% N-2). High resolution transmission electron microscopy and fast Fourier transformation analysis reveal that the {115} planes are shifted upward and downward by 0.92 Angstrom along {115} plane after forming gas annealing, resulting in (00l) planes inclined by 9.54degrees. This shifted distance of 0.92 Angstrom means that the perovskite structure is distorted by 29.98% compared to the normal interatomic distance of 3.077 Angstrom. This distorted perovskite structure results in degradation of ferroelectric properties. However, this lattice deformation and ferroelectric property of SBN films are recovered after annealing in oxygen ambient. (C) 2004 American Institute of Physics.